Lawyers have called for an inquiry into the prosecution of a man accused of violent disorder at demonstrations after claiming that the police delayed releasing vital video footage which proved his innocence.

The case against Jake Smith was dropped at Isleworth crown court yesterday when the prosecution barrister said a review of video evidence "very much undermined" their case.

He was originally accused of two counts of violent disorder at two separate protests outside the Israeli embassy in January last year. Police submitted video evidence to support their case, which they said showed Smith throwing a stick in one case and pushing barricades towards police lines in another.

However outside court Smith's lawyers said the police and prosecutors had failed to provide vital video footage for more than a year that showed Smith being hit by officers with batons and shields.

"The police presented a wholly false picture of my client," said Matt Foot, of solicitors Birnberg Pierce. "What the police initially showed of my client's involvement in the demonstration was a cut and paste job, and it is only with persistence that you get to see the true picture at the police station two days before the case is due to be heard. You can't ambush an innocent man like that."

Foot said the crucial evidence showing the police attacking Smith only came to light by chance when his client came across a video clip on YouTube which appeared to show him being beaten by officers in riot gear.

Despite this Foot said the Metropolitan police denied they had any more footage of Smith from the demonstration for more than a year. On the last working day before the trial was due to take place he was told they had seven and a half hours of footage which might be relevant.

After hours of searching the police archive Smith's legal team found footage of his client pushing the barricades – and moments before of him being beaten by the police.

"There is no way I would have found this unless we hadn't stumbled across the YouTube footage," said Foot.

He also found footage that the court heard proved Smith could not have thrown the stick.

"It shows that the man who threw the stick ran away – and the camera then pans forward to show Smith still marching with the demonstration holding a Love Jews, Condemn Israel placard," said Foot.

Yesterday, Karen Robinson, prosecuting, said the crown was dropping the case against Smith because, in one case, the video evidence had been reviewed and found to be of "insufficient quality" and in the second instance new footage had been uncovered which "very much undermined" the prosecution's case.

Defending, Nick Wrack said the police had only released partial evidence and the new footage showed Smith had been the subject of a "violent attack".

Outside the court Foot said both police and prosecutors had questions to answer about the way the case was handled.

"The police released only partial and selective data until the 11th hour and until that point the prosecution didn't allow us access to the data so they are equally culpable," he said.

The demonstrations against the Israeli invasion of Gaza held outside the Israeli embassy resulted in more than 70 people being arrested, the vast majority Muslims. Campaigners have claimed that offenders have been treated harshly by the police and the courts. Smith was one of the minority of those charged who pleaded not guilty.

After the case against him collapsed Smith, a journalism student at the time of the demonstration, said he was "relieved but angry.

"I've been on bail for more than a year and it's really messed up my life. I had no idea the police could behave like that. They were spitting at me, beating me on the head, and I would have been the one doing three years in jail if I'd been found guilty. Where's the justice in that?"

Foot said he would be writing to the Independent Police Complaints Commission to call for an independent inquiry into the way the video evidence in the case had been handled.

Kris Venkatasami, district crown prosecutor for Isleworth and Kingston, insisted that the CPS had not withheld any evidence. Today he said: "The case against Jake Smith was discontinued when further evidence was made available to the prosecution which had only been drawn to our attention by the police three months after Mr Smith was charged. This video footage, which had not previously been seen by the CPS, supported a contention that Mr Smith may have acted in self-defence. Accordingly there was no longer a realistic prospect of conviction.

"The Crown Prosecution Service did not withhold any evidence from the defence team. All footage which was marked by the police as relevant to the case was made available to the defence from the early stages of the prosecution. The section of footage in question was not brought to our attention as relevant to the case and so it was not disclosed until after we received the defence case statement. At this point it was made available at the earliest opportunity."

A spokesman for the Metropolitan police said: "When police received the defence statement they reviewed the video footage. Based upon the new information disclosed, they identified an incident that was captured on police video footage. This was then offered to the defence as part of the ongoing process of disclosure. On the basis of this new evidence the prosecution offered no evidence."